Recent efforts have employed organic components for use in solar cells. Organic and composite photovoltaic cells have the advantages of being lightweight, cost-effective in processing, and can be deposited onto low-cost flexible substrates. This makes them extremely attractive for commercial applications in photovoltaic technologies.
For example, U.S. Pat. No. 6,946,597 issued to Sager et al. discloses a photovoltaic device which includes a porous template (aluminum oxide, titanium oxide, silicon oxide (SiO), other metal oxides, or other oxides) having an array of template pores. A first charge-transfer material (which may include cadmium selenide (CdSe), cadmium sulfide (CdS), cadmium telluride (CdTe). A second charge-transfer material such as an organic material fills additional space not occupied by the first charge-transfer material.
U.S. Pat. No. 6,281,430 issued to Lupo et al. discloses an photovoltaic device which includes forming columnar structures of a discotic liquid crystal material having interspaces defined between the columns of the discotic liquid crystal material, and filling the interspaces with a second material having electric properties different from that of the discotic liquid crystal material such as a low melting point amorphous phase n-type oxadiazole.
U.S. Patent Application Publication No. 2001/0036747 by Solanky et al. discloses forming porous silicon films for photovoltaic cells. The process includes electrochemical etching using an HF solution. A mechanical treatment may be employed to obtain lift-off of the low porosity layer and part of the high-porosity layer from the substrate. The mechanical treatment can be any of the known treatments such as ultrasonic treatment, pulling, etc. With the technique of formation and lift-off (separation) of thin film from the substrate, the remaining wafer (after removing thin layer) can be used again as starting product for manufacturing more thin films.
U.S. Pat. No. 6,653,701 issued to Yamazaki, et al. discloses solar cells having an inorganic semiconductor layer, a porous semiconductor layer, and an organic substance layer absorbed into the porous semiconductor layer. The inorganic semiconductor layer may be silicon, a compound semiconductor (GaAs), or a metal oxide. The porous semiconductor layer is preferably a metal oxide such as TiO2 (titanium oxide).
There is a need for further methods for fabricating solar cells based on nanostructured semiconductors and organic materials.